Abstract
BackgroundAntigen B (EgAgB) is a major protein produced by the metacestode cyst of Echinococcus granulosus, the causative agent of cystic hydatid disease. This protein has been shown to play an important role in modulating host immune responses, although its precise biological function still remains unknown. It is generally accepted that EgAgB is comprised of a gene family of five subfamilies which are highly polymorphic, but the actual number of genes present is unknown.Methodology/Principal FindingsBased on published sequences for the family, we designed specific primers for each subfamily and used PCR to amplify them from genomic DNA isolated from individual mature adult worms (MAW) taken from an experimentally infected dog in China and individual larval protoscoleces (PSC) excised from a single hydatid cyst taken from an Australian kangaroo. We then used real-time PCR to measure expression of each of the genes comprising the five EgAgB subfamilies in all life-cycle stages including the oncosphere (ONC).Conclusions/SignificanceBased on sequence alignment analysis, we found that the EgAgB gene family comprises at least ten unique genes. Each of the genes was identical in both larval and adult E. granulosus isolates collected from two geographical areas (different continents). DNA alignment comparisons with EgAgB sequences deposited in GenBank databases showed that each gene in the gene family is highly conserved within E. granulosus, which contradicts previous studies claiming significant variation and polymorphism in EgAgB. Quantitative PCR analysis revealed that the genes were differentially expressed in different life-cycle stages of E. granulosus with EgAgB3 expressed predominantly in all stages. These findings are fundamental for determining the expression and the biological function of antigen B.
Highlights
Antigen B (EgAgB) is the most abundant protein generated by the pathogenic larval stage of Echinococcus granulosus, the cause of cystic echinococcosis (CE)
Antigen B (EgAgB) is a major protein produced by the metacestode cyst of Echinococcus granulosus and plays an important role in modulating host immune responses, its precise biological function still remains unknown
Based on sequence alignment analysis, we found that the gene family comprises ten unique genes
Summary
Antigen B (EgAgB) is the most abundant protein generated by the pathogenic larval stage (hydatid cyst or metacestode) of Echinococcus granulosus, the cause of cystic echinococcosis (CE). Determining the number of the genes in the family is fundamental for further exploring the expression and regulation of EgAgB in E. granulosus This will provide insight to more fully understanding its biological function in this and other. Antigen B (EgAgB) is a major protein produced by the metacestode cyst of Echinococcus granulosus, the causative agent of cystic hydatid disease. This protein has been shown to play an important role in modulating host immune responses, its precise biological function still remains unknown. It is generally accepted that EgAgB is comprised of a gene family of five subfamilies which are highly polymorphic, but the actual number of genes present is unknown
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